The present invention relates to a bolt apparatus. In particular, the apparatus finds utility as a bolt apparatus for fixation of bones such as fractures of the femur, although it may be used in any suitable bone. By “bolt apparatus” is meant an apparatus that bolts or fixes objects together, which apparatus can be used for fixation of bones.
Bone fixation devices are well known and they find particular utility in the field of orthopaedic surgery, where they are used to fix a bone, which has sustained a fracture, across a fracture site. Generally, the type of fracture determines the type of surgery.
Patients with femoral neck fractures are treated with pinning or hip arthroplasty, depending on the age of the patient and the presence and degree of displacement. Patients with intertrochanteric fractures are treated with a sliding hip screw or an intramedullary hip screw, depending on the stability and location of the fracture.
If the fracture is stable, a sliding hip screw coupled to a side plate that is screwed onto the femoral shaft is used. The screw provides proximal fragment fixation. It is set inside a telescoping barrel that allows impaction of the bone, which promotes fracture union. A lateral buttress must be intact to stop excessive sliding of the screw.
When the direction of a fracture is parallel to the femoral neck, the fracture can be extremely unstable. This fracture type is called the reverse oblique pattern. A high rate of failure occurs if the fracture is treated with a sliding hip screw and a side plate. Because of the angle of the fracture, there is no bone laterally to stop the screw from sliding.
For unstable intertrochanteric fractures, including those of the reverse oblique pattern and those with subtrochanteric extension, an intramedullary hip screw is often indicated. This device combines a sliding hip screw with an intramedullary nail. Intramedullary hip screws can be placed through small incisions, and blood loss may be less than with a hip screw and side plate. The nail acts as a metal buttress to prevent sliding and provides better fixation in unstable fracture patterns.
Failure mechanisms of a hip screw include non-union, screw cut-out, nail breakage, malunion, and limp. Although sliding of the hip screw allows for bone compression and hopefully healing, it shortens the limb and causes abduction weakness. Most complications are subsequently treated with total hip arthroplasty.